PROJECT SUMMARY The objective of this application is to advance novel peptide therapeutics for hypertension with a special focus on resistant hypertension (RH) for which there are no approved drugs or devices in the US. Our strategy is to target the particulate guanylyl cyclase receptor-A/cyclic guanosine monophosphate (pGC- A/cGMP) pathway for which the cardiac hormone ANP is an endogenous ligand. Studies to date support a key role for the pGC-A/cGMP pathway in blood pressure (BP) regulation. The mechanism of BP lowering is natriuresis, vasodilation and aldosterone suppression. Beyond BP lowering properties, this pathway also possesses anti-hypertrophic, anti-fibrotic, anti-inflammatory and endothelial protective actions. In the general population, we and others have reported a genetic variation of the ANP gene (rs5068) is associated with higher ANP, lower BP and protection from hypertension (HTN) and metabolic syndrome. We also reported that early stages of human HTN are characterized by reduced ANP, while severe HTN is characterized by lower ANP and higher aldosterone. Importantly, African Americans (AAs) represent an ethnic population at high risk for RH and are characterized by a 40% reduction in circulating natriuretic peptides (NPs) compared to other ethnic groups. The applicants designed MANP as a best-in-class pGC-A/cGMP activator, which possesses enhanced pGC-A/cGMP activating properties, and is markedly resistant to degradation by neprilysin. In experimental models, MANP is superior in lowering BP, enhancing natriuresis and suppressing aldosterone compared to ANP. In the only human study to date, once daily subcutaneous injection of MANP, for three days, in subjects with RH was well tolerated, safe and robustly reduced BP, suppressed aldosterone and enhanced sodium excretion as well as GFR. First, we propose to define the responsiveness to MANP in African Americans (AAs) with RH. Second, we will define the chronic cardiorenal protective and RAAS suppressing actions of a next generation MANP (i.e. MANP2) in spontaneously hypertensive rats (SHRs). Third, we propose to define synergism in vitro between two lead small molecule positive allosteric modulators (PAMs) with MANP2 to optimize pGC-A activation. Specific Aim 1: Define BP, CV, renal, neurohumoral, and cGMP responses of MANP in AAs with RH using Mayo Clinic's Center for Clinical and Translational Science (CCaTS) Clinical Research Unit (CRU). Specific Aim 2: Establish in vivo the chronic cardiorenal protective and RAAS suppressing properties of MANP2 in SHRs compared to Entresto. Specific Aim 3: Define synergy in pGC-A/cGMP activation, in vitro, between two lead PAMs and MANP2 in human primary cells.